I don't know the year or model either, but when I hear of a 110V electric HWH with an intermittent problem, I suggest that you should inspect the 110V wiring within the black plastic box on the back of the tank. This box also gives access to the heater element. There is more than one report of loose 110V wiring with loose connections causing problems and potential hazards.
If the problem is with the 12V relay contacts, simply replace it.
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